twi.c

来自「AT91RM9200的RTC测试程序」· C语言 代码 · 共 130 行

//*--------------------------------------------------------------------------------------
//*      ATMEL Microcontroller Software Support  -  ROUSSET  -
//*--------------------------------------------------------------------------------------
//* The software is delivered "AS IS" without warranty or condition of any
//* kind, either express, implied or statutory. This includes without
//* limitation any warranty or condition with respect to merchantability or
//* fitness for any particular purpose, or against the infringements of
//* intellectual property rights of others.
//*--------------------------------------------------------------------------------------
//* File Name           : twi.c
//* Object              : Basic TWI EEPROM driver
//* Translator          :
//* 1.0 25/11/02 NL		: Creation
//*--------------------------------------------------------------------------------------
#include "AT91RM9200.h"
#include "lib_AT91RM9200.h"
#include "twi.h"

#define AT91C_MASTER_CLOCK 60000000 // Processor clock set by the loader: 60MHz
#define AT91C_TWI_CLOCK		10000

//*=========================================================
//*		INIT
//*=========================================================
//*----------------------------------------------------------------------------
//* \fn    AT91F_SetTwiClock
//* \brief Initialization
//*----------------------------------------------------------------------------
void AT91F_SetTwiClock(const AT91PS_TWI pTwi)
{
	int sclock;

	/* Here, CKDIV = 1 and CHDIV=CLDIV  ==> CLDIV = CHDIV = 1/4*((Fmclk/FTWI) -6)*/

	sclock = (10*AT91C_MASTER_CLOCK /AT91C_TWI_CLOCK);
	if (sclock % 10 >= 5)
		sclock = (sclock /10) - 5;
	else
		sclock = (sclock /10)- 6;
	sclock = (sclock + (4 - sclock %4)) >> 2;	// div 4

    pTwi->TWI_CWGR	= 0x00010000 | sclock | (sclock << 8);
    //pTwi->TWI_CWGR = 0x1ffff;
}

//*=========================================================
//*		WRITE
//*=========================================================
//*----------------------------------------------------------------------------
//* \fn    AT91F_TWI_Write
//* \brief Send n bytes to a slave device
//*----------------------------------------------------------------------------
int AT91F_TWI_Write(const AT91PS_TWI pTwi ,int address, char *data2send, int size)
{
	unsigned int status;

	// Set the TWI Master Mode Register
	pTwi->TWI_MMR = ( AT91C_EEPROM_I2C_ADDRESS | AT91C_TWI_IADRSZ_1_BYTE ) & ~AT91C_TWI_MREAD;	
	
	// Set TWI Internal Address Register
	pTwi->TWI_IADR = address;

	status = pTwi->TWI_SR;
		
	pTwi->TWI_THR = *(data2send++);
	
	pTwi->TWI_CR = AT91C_TWI_START;
		
	while (size-- >1){

		// Wait THR Holding register to be empty
		while (!(pTwi->TWI_SR & AT91C_TWI_TXRDY));
	
		// Send first byte
		pTwi->TWI_THR = *(data2send++);
		
	}

	pTwi->TWI_CR = AT91C_TWI_STOP;		

	status = pTwi->TWI_SR;

	// Wait transfer is finished
    while (!(pTwi->TWI_SR & AT91C_TWI_TXCOMP));
		
	return AT91C_EEPROM_WRITE_OK;
}

//*=========================================================
//*		READ
//*=========================================================
//*----------------------------------------------------------------------------
//* \fn    AT91F_TWI_Read
//* \brief Read n bytes from a slave device
//*----------------------------------------------------------------------------
int AT91F_TWI_Read(const AT91PS_TWI pTwi , int address, char *data, int size)
{
	unsigned int status;
	
	// Set the TWI Master Mode Register
	pTwi->TWI_MMR = AT91C_EEPROM_I2C_ADDRESS | AT91C_TWI_IADRSZ_1_BYTE | AT91C_TWI_MREAD;	
	
	// Set TWI Internal Address Register
	pTwi->TWI_IADR = address;
	
	// Start transfer
	pTwi->TWI_CR |= AT91C_TWI_START;
		
	while (size-- >1){
		
		// Wait RHR Holding register is full
		while (!(pTwi->TWI_SR & AT91C_TWI_RXRDY));

		// Read byte
		*(data++) = pTwi->TWI_RHR;
	
	}
	
	pTwi->TWI_CR |= AT91C_TWI_STOP;

	//status = pTwi->TWI_SR;

	// Wait transfer is finished
    while (!(pTwi->TWI_SR & AT91C_TWI_TXCOMP));

	// Read last byte
	*data = pTwi->TWI_RHR;
		
	return AT91C_EEPROM_READ_OK;
}